Cambodia-Vietnam relations have long been turbulent. Occupation, conflict
and political meddling have been hallmarks of the relationship, and
disagreement about the border has long been a bone of contention. Last year a
group of 600 protesters burned a Vietnamese flag outside the embassy in Phnom
Penh, earning a strong rebuke from Hanoi.

Tensions have continued to simmer since. In June, Cambodian activists
clashed with Vietnamese villagers in Svay Rieng province, which lies between
Phnom Penh and Ho Chi Minh City, while Cambodian police looked on.

This week, tensions have also bubbled over around maritime borders.

Both Hanoi and Phnom Penh are seeking a speedy resolution to demarcate the
problematic land border. The process is 80% complete. Yet as it draws closer to
being finalised there is an increasing risk of further problems. Following a
three-day meeting in early July, the two parties agreed to complete the
demarcation 'very soon'.

But given the highly politicised nature of the issue, that deadline may
prove difficult to meet. The border dispute is testing Cambodia's Prime
Minister Hun Sen. Memories are long and many Cambodians still see him as a
Vietnamese puppet (he was part of the the government installed by Hanoi
following the Vietnamese overthrow of the Khmer Rouge in 1979). Anger will grow
if the border deal isn't seen as favourable.

Sam Rainsy, the opposition leader, has for almost two decades employed
xenophobic rhetoric against the Vietnamese.

In 1998 he campaigned on a ticket to expel the yuon, a derogatory Khmer term
used for the Vietnamese. Little has changed since. In 2009 Rainsy led a group
of activists on a visit to disputed territory along the Vietnamese border where
they uprooted a demarcation post. This populist move saw him sentenced to two
years in jail, after which he fled into self-exile until in 2013, when he
received a royal pardon, returning to contest the elections. His tactics
haven't changed. Disputes with Vietnam are the oxygen for much of his and the
Cambodian National Rescue Party's popularity.

The CNRP claims that current negotiations over demarcation are using
Vietnamese maps and are thus unfavourable to Cambodia. Such claims play well
with many Cambodians, and Hun Sen has looked to quell such assertions by
requesting maps from the UN drawn up during French rule.

Worryingly, decades of skirmishes between Cambodia and Thailand around the
disputed territory of Preah Vihear Temple may indicate to some Cambodians that
violence gets results. This concern is exacerbated by the fact that Cambodia is
undergoing a period of heightened political uncertainty. The 2013 elections
left Hun Sen weakened, with the opposition nearly doubling its share of seats
in the national assembly. Months of subsequent political deadlock resulted in
concessions being granted to the CNRP. The Opposition has increased its
influence in politics and is frustrating Hun Sen's usually firm control, and
the border issue could further strengthen support for the CNRP. Coupled with
persistent grievances toward deep-rooted corruption, inequality and the
enrichment of the elites that support Hun Sen, this could create a perfect
storm for the ruling Cambodian People's Party.

Hun Sen, a master strategist who has maintained a grip on power for three
decades, has recently made moves to strengthen his own hand. In July, 11
opposition activists were jailed for 'insurrection' for their role in last
year's protests, and a law that will restrict the operations of NGOs (and
inhibit their criticisms of government) was passed.

In recent weeks Hun Sen and his defence minister have warned the military to
be vigilant and ready to suppress any attempt at a 'colour revolution'. Much of
the oxygen for such a 'revolution' could come from the border dispute,
particularly if there is anger over any perceived ceding of territory to
Vietnam.

Phnom Penh isn't the only party that wants to see the back of the
demarcation process.

For Hanoi, resolving border disputes is one way of hitting back at what it
feels is its growing isolation. Both Cambodia and Laos are increasingly
influenced by Beijing, thanks to significant Chinese investment. Hanoi worries
that Cambodia, which many see as a quasi-vassal state of China, could be
manipulated to create problems along the border with Vietnam. Such concerns
have lingered since 2012 when Phnom Penh prevented any ASEAN unity against
Chinese assertiveness in the South China Sea. Vietnam worries that Phnom Penh
could escalate the border dispute as a distraction from any incident with China
in the South China Sea. In such a situation, Hanoi could be in hot conflict
with its two biggest neighbours on two very different fronts.

Hanoi's sense of isolation has no doubt factored into its attempts in recent
years to develop a more proactive and open foreign policy characterised by a
long-held motto of 'fewer enemies, more friends'. Most telling is the recent
warming of relations with the US – last month's visit to Washington by the
general secretary of the Communist Party of Vietnam was a first.

ASEAN, the UN and other governments should support and indeed insist on the
speedy resolution of the border dispute. While it could be settled in the
Hague, much like the 2013 settlement of the Preah Vihear case, this would be a
lengthy process which would ignite more nationalism. And Hun Sen is all too
aware that the longer the process drags on, the more it plays into the hands of
the opposition ahead of promised elections in 2018. For its part, Hanoi would
be happier with the current Hun Sen Government than an unknown and seemingly
anti-Vietnamese one in Phnom Penh, though it would no doubt prefer a government
less influenced by Beijing.

How the border disputes are resolved will be an important indicator of
Cambodia's stability and how Vietnam and Cambodia can work together on an issue
of mutual interest.